slate

slate,

fine-grained rockrock,aggregation of solid matter composed of one or more of the minerals forming the earth's crust. The scientific study of rocks is called petrology. Rocks are commonly divided, according to their origin, into three major classes—igneous, sedimentary, and metamorphic......Click the link for more information. formed when sedimentary rocks such as shaleshale,sedimentary rock formed by the consolidation of mud or clay, having the property of splitting into thin layers parallel to its bedding planes. Shale tends to be fissile, i.e., it tends to split along planar surfaces between the layers of stratified rock......Click the link for more information. are metamorphosed by great pressure. Slate splits into perfectly cleaved, broad thin layers; this characteristically regular and planar cleavage is called slaty cleavage. In the formation of slate, pressure causes the flaky minerals within the sedimentary rock, such as mica, clay, and chlorite, to be reoriented; the flat faces of the minerals lie at right angles to the source of the pressure, and the planes of easy cleavage are also at right angles to the source of the pressure. The rock is not necessarily compressed in the same direction as the sedimentary layers were originally laid down, and because the compression crumples and deforms the original sedimentary layers, the planes of slaty cleavage usually cut through the old bedding planes. Slate is intermediate in hardness between mica schistsschist, metamorphic rock having a foliated, or plated, structure called schistosity in which the component flaky minerals are visible to the naked eye. Schists are distinguished from the other foliated rocks, slates and gneisses, by the size of their mineral crystals; these are.....Click the link for more information. and shale; the better grades are used for roofing. Its characteristic color is gray-blue. Slate is mined in Maine, Vermont, Pennsylvania, Georgia, Lake Superior, and the Rocky Mts.

slate

A hard, brittle metamorphic rock characterized by good cleavage along parallel planes; used as cut stone in thin sheets for flooring, roofing, and panels, and in granular form as surfacing on composition roofing.

Slate

a schistous, sedimentary rock used for roofing. It consists of argillaceous minerals (for the most part, various hydromicas and chlorite) whose particles are usually arranged in strictly parallel lines. This structure gives slate a sharply defined schistosity, that is, the capacity for cleavage into thin lamina. Slate does not fall apart in water and has the characteristics of geosynclinal sediments. It is formed by the compaction of clays and their partial recrystallization under pressure at considerable depths as well as by the effect of dynamic metamorphism. When it undergoes further change, it becomes a phyllte or a chlorite slate.

The largest known deposits of slate in the USSR are located in the Caucasus and the Urals. Slate is used as roofing material; in the production of low-voltage switchboards, knife switches, and other apparatus in the electrical industry; and in the production of certain structural components (panels for the interior facing of rooms). Slate is also used in a crushed, roasted, and aerated form as filler for certain types of concrete, large wall blocks, and for cladding ruberoid(roof-sheeting material).

V. P. PETROV

slate

[slāt]

(petrology)

A group name for various very-fine-grained rocks derived from mudstone, siltstone, and other clayey sediment as a result of low-degree regional metamorphism; characterized by perfect fissility or slaty cleavage which is a regular or perfect planar schistosity.

slate

A hard, brittle metamorphic rock consisting mainly of clay minerals, characterized by good cleavage along parallel planes; used extensively as dimension stone in thin sheets for flooring, roofing, panels (both decorative and electrical), and chalkboard, and in granular form as surfacing on composition roofing.

slate

1.

a. a compact fine-grained metamorphic rock formed by the effects of heat and pressure on shale. It can be split into thin layers along natural cleavage planes and is used as a roofing and paving material

b. (as modifier): a slate tile

2. a dark grey colour, often with a purplish or bluish tinge

3.Chiefly US and Canadian a list of candidates in an election

4.Films

a. the reference information written on a clapperboard

b.Informal the clapperboard itself

slate

Another name for a tablet. In 2010, HP introduced tablets under the Slate brand. See Tablet PC and tablet.

“I’ve known a smart chase, and a fight at the tail of it”, where less has been logged than I’ve got on that there slate. Howsomnever, they didn’t come to facers, only passed a little jaw fore and aft.”

By ERYL CRUMP Daily Post Chief Reporter eryl.crump@trinitymirror.com A PS2m scheme to refurbish former council houses in a Snowdonia village will see the properties roofed with Spanish slate. Work to improve the houses on the Dol Eilian estate at Llanberis has already begun.

"The slates will then go back on the repaired roof for the next 100 to 150 years or so," said Judith Green, secretary of the church's environment and heritage group, which has been restoring the churchyard.

Disputes between the two slates go back to January 2009 when Hadba' Slate took over all of the provincial council's upper posts after having won 19 out of the Council's 37 seats, while Niniveh Fraternal Slate, headed by Khisro Koran, got only 12 seats forcing it to boycott the Council taking with it 16 administrative entities.

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